A Zeiss IM-35 inverted microscope was modified to employ FCS methods. The camera port was used for this purpose, allowing the easy performance of both microscopy and FCS detection at the same time. Illumination is performed replacing the arc lamp by a laser. For detection, fiber coupled avalanche photodiodes are used where the fiber diameter serves as a pinhole thats size can be easily varied. Filters and dichroic mirrors are can be exchanged like usual in this kind of microscopes.